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Completed project

Australian Citrus Quality Standards – stage 3 (CT15013)

Key research provider: Citrus Australia
Publication date: Friday, May 10, 2019

What was it all about?

Established in 2011 and now in its third stage, the Australian Citrus Quality Standards program has a focus on improving and maintaining the eating quality of Australian citrus – ensuring fruit consistently meets or exceeds consumer expectations. The overarching goal is to increase consumption and ensure the price of Australian citrus is maximised.

This stage of the project, which ran from 2016 to 2018, set out to improve the standard of oranges and mandarins. To achieve this consistency, the project defined six areas of activity that included:

  • Testing and reporting maturity levels of fruit for sale in Australian wholesale markets
  • Developing and implementing a maximum granulation standard for Imperial mandarins
  • Engaging the national supply-chain and strengthening linkages
  • Developing a Standard Operating Procedure for commencing harvest
  • Conducting pre-harvest field testing and communicating results to industry participants
  • Collaborating with the research community to improve the quality of Australian citrus.

Citrus fruits are non-climacteric, so they don’t develop sugars after harvest. Harvest must therefore be timed precisely for best quality. To help growers to get the timing right, the team investigated the best practice for harvest, as well as modifying protocols for fruit testing to make it a more accurate guide for growers.  

Currently, juice from several fruit is extracted and combined to measure sugar and acid content to judge harvest readiness, but this underestimates the effect of variation between fruit. The team modified in-field and market testing protocols so that testing was conducted on individual fruit within samples. This gave a better understanding of the variability within orchards and commercial consignments.

Given the variation in samples, protocols were also changed to sampling 30 fruit rather than just ten, to provide reliable ratings.

Standard operating procedures

As a result of this work, the project team developed a Standard Operating Procedure (SOP) for harvest, which growers can use to reliably assess fruit maturity, preventing immature fruit from being consigned to market. The SOP was developed in consultation with Citrus Australia’s Domestic Leadership Group and incorporates industry best practice and existing procedures in California and New Zealand. The SOP was released as a guideline on the Citrus Australia website.


Granulation, or internal dryness, can be a problem in Imperial mandarins, so another aspect of the project developed a granulation standard that market testing agents and retailers can use to visually detect, grade and report granulation.

A sensory evaluation study by the University of Queensland concluded that mandarins granulated at the 35 per cent and 45 per cent levels are acceptable to consumers, but not above 55 per cent. Accordingly, a visual guide was developed that shows the entire spectrum of granulation with acceptable limits.


Linkages between the supply-chain and the research community were further developed through the project with all making contributions towards the project. In 2017, the project team participated in ‘Would I buy it?” panels with a major retailer. Findings from those panels have informed the retailer’s citrus product specifications which include a hybridised version of the Australian Citrus Quality Standards.

Citrus Australia’s industry forums were platforms for the supply-chain and researchers to network and communicate findings. Levy-funded communication channels were also used to get news out

Over the course of the project, there has been a greater level of awareness of consumer expectations and effort to deliver upon those expectations among growers. Similarly, through engagement with growers, packers and retailers, there is a greater technical ability to conduct product testing, coupled with a genuine effort to only supply mature fruit to market.

In the three years of the project, 83 per cent of fruit tested either achieved or exceeded the Australian Citrus Quality Standard. 


Related levy funds

This project was a strategic levy investment in the Hort Innovation Citrus Fund